Signs intended for use as directories typically display the names of various persons or other entities together with their office numbers or locations. For example, the typical directory sign located in the lobby of a building will name the firms or organizations located in that building, and possibly the names of at least some individuals therein, together with information such as room numbers or building floors where particular persons or organizations are located. The contents of these signs are updated from time to time as people come and go within the locations covered by the sign.
Signs intended for use as directories and the like usually are designed so that individual names or addresses can be changed without the need to fabricate a new display panel containing all information on the sign. In this way, the cost and ease of replacing only one or a few names is much less than if that same number of changes required replacing the entire information display of the sign. For example, replacing it is known in the art to provide directory signs in which each name or other directory location appears on an individual message panel which forms part of the overall sign. The directory sign, thus, is composed of a number of those message panels displayed in a desired alphabetical or other arrangement, and mounted within a frame or other structure defining the overall sign. Such signs may include receptacles or other positioning structure to locate each individual message display panel in a fixed location or a predetermined array of locations on the sign, so that the resulting array of numerous message panels provides an attractive uniform appearance resembling a single overall monolithic display, rather than a composite of numerous individual message panels.
Those skilled in the art will recognize different techniques for attaching the individual message display panels within directory signs of the prior art. Generally speaking, each such display panel should be individually removable and attachable without disturbing adjacent panels making up the sign. Moreover, removing a particular message display panel and replacing it with a new one should take minimum time and require no unique tools, so that the cost of maintaining and installing a directory sign can be minimized. In an effort to meet these and other functional requirements, various techniques are known for attaching individual message panels to directory signs and the like. For example, each message panel can be provided with an adhesive backing layer such as double-sided adhesive tape for adhering the individual panels to a vertical substrate forming part of the overall sign assembly. The use of such adhesive fastening techniques alone, however, requires selecting an adhesive that remains effective over the expected lifetime of the sign, without diminishing due to aging or extremes of temperature or humidity. Although such adhesives are known, their desirable characteristics mean that intentional removal of a particular message panel often is accomplished only with considerable difficulty, sometimes including damage to the sign itself. This creates a problem where removing only one message panel of a directory sign also requires relocating a number of other message panels of the sign, because each relocated message panel must first be removed from its original location on the sign.
Another technique for removably affixing individual message panels to a directory sign requires individual mounting studs affixed to the back side of each message panel. These mounting studs are pressed into corresponding holes drilled or otherwise formed for the purpose in one or more members located behind the plane of the message panels. This mounting technique requires precise lateral and vertical alignment of the studs on the individual message panels, and also of the holes for receiving those studs, so that the resulting directory sign maintains a uniform appearance of all message panels making up the sign. As a result, directory signs using this prior-art technique are relatively expensive to assemble and maintain. Moreover, the backing holes usually are formed at periodic intervals along the backing member, making it difficult to include message panels or divider strips having an irregular width or shape.